This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 8 |
| 4 | 18 |
| 5 | 44 |
| 6 | 112 |
| 7 | 288 |
| 8 | 744 |
| 9 | 1938 |
| 10 | 5104 |
| 11 | 13584 |
| 12 | 36456 |
| 13 | 98468 |
| 14 | 267376 |
| 15 | 729488 |
| 16 | 1999074 |
| 17 | 5500412 |
| 18 | 15189636 |
| 19 | 42084952 |
| 20 | 116949848 |
| 21 | 325878288 |
| 22 | 910333152 |
| 23 | 2548892864 |
| 24 | 7152113760 |
| 25 | 20108587038 |
| 26 | 56641227416 |
| 27 | 159820928328 |